Field
The present disclosure is related to filtration systems, and more particularly, to filtration systems in which a filter media extends across an influent/effluent interface, to filter out particulates, solids, and other entrained materials from the fluid as the fluid passes through the filter media, such fluid including water being treated in a wastewater treatment facility. More particularly still, the present disclosure is related to improved filtration systems having enhanced serviceability, smaller footprint, fewer individual unique parts, and which can be backwashed for cleaning of the filter media without taking the filtration system offline.
Description of the Related Art
Filtration systems are commonly employed to treat wastewater or other fluids to remove (filter) entrained materials therefrom. Such systems may include a plurality of individual filter manifolds or plenums, having a filter media mounted thereto covering an opening therein, typically on the exterior of the manifold or plenum, interposed between the influent and effluent side of a fluid stream in a tank or other enclosure such as an in-ground basin or other containment volume. In these systems, each manifold or plenum includes an opening therein which is covered by the filter media, an interior volume through which filtered (effluent) fluid may flow, and an effluent opening from which filtered fluid exits the manifold or plenum for further processing or reuse. The manifold or plenum and filter media together is often termed a “disk”.
In one construct, the manifolds are box like enclosures having an opening on each of the opposed sides thereof which is covered by the filter media. These structures may be located, side by side with a gap therebetween, such that the filter media on the exterior of two adjacent manifolds may face each other across an area of fluid influent extending therebetween, wherein the fluid influent may pass through each filter media and thus be filtered thereby, and thence into the interior of two different and adjacent box-like manifolds, and thence to an effluent exhaust channel. Each manifold includes an effluent outlet extending from the underside thereof, which is sealingly coupled to an effluent master drain extending along and above the base of the tank in which the manifolds are installed. In these apparatus, fluid filtration is a function of gravity, i.e., the effluent exit of the tank is at a height lower than the level of the influent in the tank, and thus, the fluid flows from the influent to effluent sides of the tank without the need for dedicated fluid pumps to pump the fluid being filtered through the filtering apparatus. However, in these systems the piping to remove the filtered effluent is located below the filter media boxes, adding height and complexity to the system and requiring a deeper tank or other enclosure volume.
Over time, the filtered particulates which are captured by the filter media, commonly called filter “cake”, is of sufficient density, thickness or quantity on and in the filter media that the gravity head of fluid required to maintain a desired flow quantity from the influent to effluent side of the tank is undesirably increased.
To maintain an acceptable hydraulic profile through the filter, a cleaning device commonly called a “backwash shoe” is passed over the surface of the filter media to remove, by flowing fluid into the backwash shoe in the immediate vicinity of the filter media surface, the filtered particulate material from the surface of the filter media. Such a backwash shoe is passed over the filter media in situ, i.e., during the flow of fluid through the filtering media, to restore the filter media to close to the original, clean, condition thereof. The shoe may be single sided, and thus remove filtered particulates from the filter media on only one side of the manifold disk, or may be double sided, i.e., have openings on the opposite sides thereof, to simultaneously remove filtered particulates from the facing filter media on two adjacent manifolds. However, at the first and last manifold of a plurality of spaced, generally parallel, manifolds, only one surface exists from which the backwash shoe can remove the filtered particulates, i.e., the filter surface at these locations does not face another manifold, but instead faces the wall of the tank. As a result, a backwash shoe having different flow properties than the double sided backwash shoe is needed to remove the accumulated particulates at these locations, which can lead to undesirable hydraulic imbalances in the filter unit. Additionally, the backwash shoe is often spring loaded to be pushed into the filter media as it scans the filter media, which can cause wear to, and premature replacement of, the filter media.